import { AsyncIterableX } from './asynciterablex';
export declare class UnionAsyncIterable<TSource> extends AsyncIterableX<TSource> {
    private _left;
    private _right;
    private _comparer;
    constructor(left: AsyncIterable<TSource>, right: AsyncIterable<TSource>, comparer: (x: TSource, y: TSource) => boolean | Promise<boolean>);
    [Symbol.asyncIterator](): AsyncIterableIterator<TSource>;
}
export declare function union<TSource>(left: AsyncIterable<TSource>, right: AsyncIterable<TSource>, comparer?: (x: TSource, y: TSource) => boolean | Promise<boolean>): AsyncIterableX<TSource>;